INTRODUCTION: Alpha-mannosidosis is an ultra-rare lysosomal storage disorder resulting from the deficient activity
of lysosomal alpha-mannosidase. Alpha-mannosidosis presents as a highly heterogenous condition with large
variations in symptom severity and disease progression rates. Quantitative and qualitative data for alphamannosidosis patients and their caregivers provide important insights into their daily experiences.
METHODS: A survey of nine alpha-mannosidosis patients was carried out in the UK between August 2017 and
January 2018. Patient demographics, health-related quality of life (HRQoL), and qualitative data from patients
and carers relating to clinical characteristics and impact of the disease and treatment were analysed.
RESULTS: At the time of survey completion, patient age ranged from 7 to 37 years. Five patients were described as
‘walking unassisted’, one as ‘walking with assistance’, one as ‘wheelchair-dependent’, and two as ‘severely immobile’. In addition to best supportive care, three patients had received haematopoietic stem cell transplantation
(HSCT) and one had received velmanase alfa enzyme replacement therapy (ERT). Patient HRQoL results for the
EQ-5D-5 L questionnaire and the Health Utilities Index-3 showed that patients with more severe ambulatory
health states reported lower utility values than patients who were more mobile. Patients who received HSCT or
ERT experienced improved HRQoL. Carer HRQoL results for the Hospital Anxiety and Depression Scale and
Caregiver Strain Index demonstrated that carers experience high levels of stress and anxiety from their caregiving responsibilities.
CONCLUSIONS: This survey confirmed the heterogeneity of alpha-mannosidosis and the large impact of the disease
and treatment on patients, carers, and families. Early diagnosis and access to treatment offers the best chance of
slowing the disease progression and may provide some relief to patients and carers.
Supplementary Material 1: EQ-5D-5L domains walking ability results